Typically, gas turbine engines include a compressor for compressing air, a combustor for mixing the compressed air with fuel and igniting the mixture, and a turbine blade assembly for producing power. Combustors often operate at high temperatures that may exceed 2,500 degrees Fahrenheit. Typical turbine combustor configurations expose turbine blade assemblies to these high temperatures. As a result, turbine blades must be made of materials capable of withstanding such high temperatures. In addition, turbine blades often contain cooling systems for prolonging the life of the blades and reducing the likelihood of failure as a result of excessive temperatures.
The blade tip region is an area of particularly high thermal stress which is exposed to high heat load due to high external heat transfer coefficients in this region and ineffective convective cooling due to its geometry. Migration of mid-span hot gas to the blade tip region also contributes to the problem. Typical blade designs, illustrated in FIG. 1 by a sectional view of a blade 100 having a pressure side 102 and a suction side 104, rely on extensive film cooling to reduce the gas temperature in contact with the blade tip end 106. Common film cooling arrangements use one row of holes 108 on the pressure side 102 of the blade 100 just below the tip end 106, illustrated in FIG. 1 as a squealer having a rail 110 defining a squealer cavity 112, and several rows of holes 114 through the floor 116 of the squealer cavity 112 of the tip end 106. The large number of film holes 108, 110 requires a large amount of cooling air flow which may compromise the performance of the gas turbine.